8o 
Notes on Recent Literature. 
conditions, Pirus communis, for example, reaching 44 n C above the 
surrounding air, while Hedera helix only reached 6‘6 n C and succulent 
leaves of Bergeria only 3'5° above the surrounding air of the room. 
Molisch attributes this to the sluggish respiration occurring in 
succulent and stiff leaves. He does not, however, make any con¬ 
firmatory measurements of the rate of respiration in his leaves. 
He carried out experiments proving that the rise of temperature 
was not due to increase of respiration caused by the wounding of 
the petiole in cutting off the leaf. He also used wet leaves and 
found them to rise in temperature much more slowly than dry 
leaves. This had the effect of bringing the two maxima of the 
usual curve together to form one. He attributes this slower rise of 
temperature partly to the effect of water in stopping up the stomata 
and thus hindering respiration, and partly to the better conduction 
of heat from the mass when the spaces between the leaves are filled 
by water and not air. It is more likely that it is principally due to 
the amount of heat required to slowly vaporise the water at these 
temperatures. . 
Though at first sight it is surprising that such high temperatures 
should be attained due to respiration alone, yet when arrangements 
are made for preventing loss of heat by radiation, conduction, &c., 
the slight rise of temperature due to respiration in each leaf must 
have a cumulative effect, and the temperature will rise until heat 
gained and heat lost are equal. 
When such an equilibrium is attained the temperature will 
probably be a fairly exact measure of the intensity of respiration. 
It is interesting thus to find in some cases that the slackening of 
respiration still occurs, although the first maximal point was below 
death-point for the leaves. This falling off is attributed by Molisch, 
with a great degree of probability, to the exhaustion of the carbo¬ 
hydrate reserve at first present in the leaf. An instance of continuous 
rise in temperature in pear leaves after death-point had been reached, 
and before tbe activity of bacteria had set in, is attributed to post¬ 
mortem breaking-down changes due to the activity of oxidases. 
A.M.S. 
BIBLIOGRAPHY. 
Ursprung, A. Bibliotheca Botanica, Stuttgart, 1903. 
Blackman and Matthaei. Proceedings, Roy. Soc., Vol. B, 76, 1905. 
Baumert, K. Beitrage z. Biol. d. Pfl., Bd. IX., Heft. II., 1907. 
Moler, T. Botaniska Notiser, 1908. 
Wiesner, J. Ber. d. D. Bot. Ges., Heft. IX., 1908. 
Molisch, H. Bot. Zeit., Dec., 1908. 
R. Mauley, Printer, 151, Whitfield Street, London, W, 
